1. Field of the Invention
The present invention relates to a method of printing in an ink jet printer, and, more particularly, to a method of underfeeding print media during printing with an ink jet printer.
2. Description of the Related Art
An ink jet printer typically includes an ink jet cartridge which is carried by a carriage assembly. The ink jet cartridge includes a printhead having a plurality of nozzles, from which ink is jetted onto the print medium at selected ink dot locations within an image area. The carriage assembly moves the printhead across the print medium in a scan direction while the ink dots are jetted onto selected pixel locations within a given raster line. Between passes of the printhead, the print medium is advanced a predetermined distance and the printhead is again scanned across the print medium.
An ink jet printer may be designed to slightly underfeed the print medium, essentially indexing a small amount short of the ideal index amount. In other words, raster lines between adjacent swaths may slightly overlap one another. This is done to hide indexing errors due to the mechanical system, as well as the software algorithm used to control this motion. The theory behind this is that a gap (or white space) between consecutively printed swaths, due to a slight overfeed error, is more visible to the user than a slightly darker line, due to an underfeed error.
Printing may occur using a single pass technique or a multiple pass technique. A multiple pass technique such as shingling is utilized to reduce print artifacts which may occur as a result of a clogged nozzle or the like by using multiple nozzles to print on a given raster line.
Intentionally underfeeding the print medium in the advance direction typically is acceptable for single pass print modes to mask indexing errors associated with the advance of the print medium. However, intentionally underfeeding the print medium during a shingling mode may cause the generation of additional print artifacts which may be objectionable.
What is needed is a method of printing which underfeeds the print medium in the advance direction only when such underfeeding results in an overall improved print quality.
The present invention provides a method of printing with an inkjet printer, wherein the print media is intentionally underfed into the print zone during single pass printing, and is not intentionally underfed into the print zone during multiple pass printing.
The invention comprises, in one form thereof, a method of printing on a print medium with an inkjet printer. The print medium is selectively printed on in a multiple pass printing mode and/or a single pass printing mode. During the single pass printing mode, the print medium is printed on in a single pass height. The print medium is advanced a distance less than the single pass height. During the multiple pass printing mode, the print medium is printed on in a multiple pass height. The multiple pass height is less than the single pass height. The print medium is advanced a distance approximately equal to the multiple pass height.
An advantage of the present invention is that the print media is fed into the print zone to take advantage of intentional underfeeding only when the benefits of such underfeeding outweigh disadvantages caused by errors induced by a given print mode.
Another advantage is that the underfeeding may selectively occur real time during actual printing.